One thing I've noticed about water and diy, it likes to mute the flavor. I read at one time or another that H2O helped bring out the flavor in blends, I respectively disagree
What it does do, however, it dilute very thick VG blends, allowing you to utilize the
juice in certain applications that otherwise would prove difficult, if not impossible, such as in a carto or clearo
tank.
I have never had a water-based flavoring, so I cannot say for sure that this is the issue at hand. What %'s are you working with? I've read some recipes that take their flavoring up towards 30-40%.